/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.metrics.metricsets.jvm;

import org.apache.iotdb.metrics.AbstractMetricService;
import org.apache.iotdb.metrics.metricsets.IMetricSet;
import org.apache.iotdb.metrics.utils.MetricLevel;
import org.apache.iotdb.metrics.utils.MetricType;

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadMXBean;
import java.util.Arrays;

/**
 * This file is modified from io.micrometer.core.instrument.binder.jvm.JvmThreadMetrics
 */
public class JvmThreadMetrics implements IMetricSet {
    @Override
    public void bindTo(AbstractMetricService metricService) {
        ThreadMXBean threadBean = ManagementFactory.getThreadMXBean();

        metricService.createAutoGauge(
                "jvm_threads_peak_threads",
                MetricLevel.IMPORTANT,
                threadBean,
                ThreadMXBean::getPeakThreadCount);

        metricService.createAutoGauge(
                "jvm_threads_daemon_threads",
                MetricLevel.IMPORTANT,
                threadBean,
                ThreadMXBean::getDaemonThreadCount);

        metricService.createAutoGauge(
                "jvm_threads_live_threads",
                MetricLevel.IMPORTANT,
                threadBean,
                ThreadMXBean::getThreadCount);

        try {
            threadBean.getAllThreadIds();
            for (Thread.State state : Thread.State.values()) {
                metricService.createAutoGauge(
                        "jvm_threads_states_threads",
                        MetricLevel.IMPORTANT,
                        threadBean,
                        (bean) -> getThreadStateCount(bean, state),
                        "state",
                        getStateTagValue(state));
            }
        } catch (Error error) {
            // An error will be thrown for unsupported operations
            // e.g. SubstrateVM does not support getAllThreadIds
        }
    }

    @Override
    public void unbindFrom(AbstractMetricService metricService) {
        ThreadMXBean threadBean = ManagementFactory.getThreadMXBean();

        metricService.remove(MetricType.AUTO_GAUGE, "jvm_threads_peak_threads");
        metricService.remove(MetricType.AUTO_GAUGE, "jvm_threads_daemon_threads");
        metricService.remove(MetricType.AUTO_GAUGE, "jvm_threads_live_threads");

        try {
            threadBean.getAllThreadIds();
            for (Thread.State state : Thread.State.values()) {
                metricService.remove(
                        MetricType.AUTO_GAUGE, "jvm_threads_states_threads", "state", getStateTagValue(state));
            }
        } catch (Error error) {
            // An error will be thrown for unsupported operations
            // e.g. SubstrateVM does not support getAllThreadIds
        }
    }

    // VisibleForTesting
    static long getThreadStateCount(ThreadMXBean threadBean, Thread.State state) {
        return Arrays.stream(threadBean.getThreadInfo(threadBean.getAllThreadIds()))
                .filter(threadInfo -> threadInfo != null && threadInfo.getThreadState() == state)
                .count();
    }

    private static String getStateTagValue(Thread.State state) {
        return state.name().toLowerCase().replace("_", "-");
    }
}
